First to go is the flimsy plastic controller. The motor shield allows up to four of the of five motor joints to be controlled with the Arduino. I want to use this opportunity to explore the Java serial libraries to communicate with the Arduino over the Internet in a Java applet *or* purchase an Arduino ethernet shield and send commands directly to the device (see below).

I suppose, as an overall goal, I would like to be able to feed my fish while away with the use of a webcam and this robotic arm.

Completed Robotic Arm connection to motor

This setup allows control of the maximum of four motors. I’d rather have everything integrated into one cable, but the supplied cable didn’t have enough pins to handle 4 motors and power and ground. That’s why I added the red/black leads shown above. Here’s how everything looks hooked up to the freshly soldered motor shield:

Right now the Arduino is powered by USB, and the motors are powered by the arm’s original DC power source — 4 D batteries. This can easily be changed to have the arm run off of a DC adapter.

Next up: Due to the number of pins that the motor shield requires, I won’t be able to use an ethernet shield with this project. So, Java-based serial communication it is!

Update 4/16/11

I wrote a Java application with SWT to handle the serial communication with the Arduino’s motor controller. Essentially, it relays messages over the serial line about what motor to enable. The “speed” of the motor is an illusion by using a custom TimerTask to repeatedly send requests to enable the motor (every 10ms) and then sleep the thread for a duration between each task interval, until the button is no longer pressed. This solution makes the robotic arm much more useful as it can now make very controlled movements (<1mm).

Here is a screen shot of the user interface:

Update 9/7/12

I’ve started working on this project again! I decided to clean up some of the code and create an Android app that can control the arm wirelessly (as long as it’s connected to a host PC).